When someone's been unfaithful, the saying "once a cheater, always a cheater" often rears its ugly head, but is there any truth to it?
A study has uncovered that people who have cheated on a partner once may be likely to cheat again, as each time a person lies, the amount of guilt they feel decreases.
The scientists, from University College London, suggested this reduction in "emotional response" can lead to people becoming serial cheaters.
"The findings uncover a biological mechanism that supports a 'slippery slope': what begins as small acts of dishonesty can escalate into larger transgressions," they said.
To test the impact lying has on our brain, scientists goaded participants into lying in order to win a cash prize.
Participants were shown a series of clear jars full of coins and instructed to help a partner, who was only shown a blurry image of the jar, to guess how many coins the jar contained.
The participants in group one were told they would receive a cash prize if their partner overestimated the number of coins in the jar, which caused many of them to exaggerate the size of the jar or lie.
The scientists noted that lying caused a response in part of the brain which is responsible for emotions - called the amygdala - but the response weakened the more times a person lied.
Although the study analysed the effects of repeated lying in general, rather than cheating specifically, co-author Neil Garrett said the principles could support the theory that people who cheat once are likely to do it again.
"The idea would be the first time we commit adultery we feel bad about it. But the next time we feel less bad and so on, with the result that we can commit adultery to a greater extent," Garrett told Elite Daily,
"What our study and others suggest is a powerful factor that prevents us from cheating is our emotional reaction to it, how bad we feel essentially, and the process of adaptation reduces this reaction, thereby allowing us to cheat more.
"With serial cheaters, it could be the case that they initially felt bad about cheating, but have cheated so much they've adapted to their ways and simply don't feel bad about cheating any more."
The study is published in the journal Nature.Suggest a correction